Current mobile electronic devices, such as smart phones, tablets and the like, incorporate one or more antennas for receiving and transmitting high-speed data. Due to the small size of such devices and high density of components on the device circuit board, interference can occur between the antenna(s) and other electronic components in close proximity thereto. For example, problems can occur when the antenna impedance match is detuned and antenna gain is degraded by the coupling of an audio transducer such as a speaker with an adjacent antenna.
It is known in the art to improve antenna performance of mobile wireless communications devices by blocking RF current from being coupled to the ground plane of a printed circuit board on which the antenna(s) and adjacent electronic components are mounted. One example of such a prior art solution is set forth in commonly-owned U.S. Pat. No. 7,483,727 entitled MOBILE WIRELESS COMMUNICATIONS DEVICE HAVING IMPROVED ANTENNA IMPEDANCE MATCH AND ANTENNA GAIN FROM RF ENERGY, issued Jan. 27, 2009, the contents of which are incorporated herein by reference.
According to the solution set forth in U.S. Pat. No. 7,483,727, the choking frequency is fixed and covers a narrow frequency band around the self-resonating frequency of the RF choke. However, modern day broadband mobile communications devices generally have different antennas implemented to support different types of wireless protocols and/or to cover different frequency ranges. For example, LTE (Long Term Evolution) bands, GSM (Global System for Mobile Communications) bands, UMTS (Universal Mobile Telecommunications System) bands, and/or WLAN (wireless local area network) bands, cover frequency ranges from 700 to 960 MHz, 1710-2170 MHz, and 2500-2700 MHz and the specific channels within these bands can vary from region to region necessitating the use of different antennas for each region in similar models of devices. It is desirable to improve antenna performance, for example in the LTE B7 range (i.e. 2500-2700 MHz).